Add JavaToScalaTransformer

ppl-spark-integration/src/main/java/org/opensearch/sql/ppl/utils/JavaToScalaTransformer.java

@@ -0,0 +1,29 @@
+/*
+ * Copyright OpenSearch Contributors
+ * SPDX-License-Identifier: Apache-2.0
+ */
+
+package org.opensearch.sql.ppl.utils;
+
+
+import scala.PartialFunction;
+import scala.runtime.AbstractPartialFunction;
+
+public interface JavaToScalaTransformer {
+    static <T> PartialFunction<T, T> toPartialFunction(
+        java.util.function.Predicate<T> isDefinedAt,
+        java.util.function.Function<T, T> apply) {
+        return new AbstractPartialFunction<T, T>() {
+            @Override
+            public boolean isDefinedAt(T t) {
+                return isDefinedAt.test(t);
+            }
+
+            @Override
+            public T apply(T t) {
+                if (isDefinedAt.test(t)) return apply.apply(t);
+                else return t;
+            }
+        };
+    }
+}